Electrolytic process for the preparation of mixed organic lead compounds and electrolyte therefor



United States Patent ELECTROLYTIC PRocEss FOR THE PREPARA- TION or MIXEDORGANIC LEAD COMPOUNDS AND ELECTROLYTE THEREFOR David G. Braithwaite,Chicago, Ill., asslgnor to Nalco Chemical Company, Chicago, Ill., acorporation of Delaware No Drawing. Continuation-impart of applicationSer. No. 811,262, May 6, 1959. This application Mar. 6, 1961, Ser. No.93,361 The portion of the term of the patent subsequent to Nov. 7, 1978,has been disclaimed 17 Claims. (Cl. 204-59) ABSTRACT OF THE DISCLOSUREAn electrolytic process for the manufacture of organic lead compoundscontaining different hydrocarbon radicals linked to the same lead atom.The electrolyte comprises a substantially anhydrous solution of at leastone Grignard reagent and at least one extraneous organic halide, theorganic radical of at least one said Grignard reagent being differentfrom the organic radical of at least one said organic halide.

electrolyte. By the term extraneous organic halide is meant an organichalide which is added as such as distinguished from the organic haliderequired to form a Grignard reagent from magnesium considering theformula of a Grignard reagent to be RMgX, Where R represents the organicradical, Mg represents magnesium, and X represents a halogen atom, suchas chlorine, bromine or iodine.

One of the objects of the present invention is to provide a new andimproved process for preparing compounds in which different organicradicals are linked to metallic lead. Other objects will appearhereinafter.

In accordance With the present invention a substantially anhydroussolution of a Grignard reagent in an organic solvent for the Grignardreagent is electrolyzed, using a lead anode, and adding extraneousorganic halide to the electrolyte, subject to the condition that theelectrolyzing action is carried out in the presence of at least twodilferent organic radicals which react with the lead. These organicradicals are supplied in several possible ways, namely (1) by employinga mixture of Grignard reagents, for example, methyl magnesium chlorideand ethyl magnesium chloride, methyl magnesium chloride and propylmagnesium chloride, methyl magnesium chloride and butyl magnesiumchloride, methyl magnesium chloride and isobutyl magnesium chloride,methyl magnesium chloride and secondary butyl magnesium chloride, methylmagnesium chloride and tertiary butyl magnesium chloride, methylmagnesium chloride and isopropyl magnesium chloride, methyl'magnesiumchloride and amyl magnesium chloride, methyl magnesium chlroide andisoamyl magnesium chloride, methyl magnesium chloride and hexylmagnesium chloride, methyl magnesium chloride and phenyl magnesiumchloride, methyl magnesium chloride and cyclohexyl magnesium chloride,methyl magnesium chloride and benzyl magnesium chloride, and adding tosuch mixture an organic halide, such as, for example, methyl chloride,ethyl chloride, propyl chloride, isopropyl chloride, butyl chloride,isobutyl chloride, secondary butyl chloride and tertiary butyl chloride,or. the corresponding bromides and iodides; or, (2) by employing as theelectrolyte a Grignard reagent in'which there is only one organicradical such as, for example, methyl magnesium chloride, ethyl magnesiumchloride, propyl magnesium chloride, butyl magnesium chloride, isobutylmagnesium chloride, secondary butyl magnesium chloride, tertiary butylmagnesium chloride, phenyl magnesium chloride, cyclohexyl magnesiumchloride, benzyl' magnesium chloride, and homologues thereof, includingthe corresponding iodides and bromides, and adding'as the extraneousorganic halide two or more organic halides, such as for example, bothmethyl chloride and ethyl chloride, both methyl chloride and isopropylchloride,'both methyl chloride and butyl chloride, both methyl chlorideand tertiary butyl chloride, and/or the corresponding bromides andiodides; or (3) mixed Grignard reagents can be used with two or moreorganic halides, such as, for example, a mixture of methyl magnesiumchloride and ethyl magnesium chloride in conjunction with the use ofboth methyl chloride and ethyl chloride as extraneous organic halides;or (4) a single Grignard reagent can be used with a single extraneousorganic halide where the organic radical of the halide is different fromthat of the Grignard reagent, for example, methyl magnesium chloride andtertiary butyl chloride. It will also be understood that differenthalogen atoms may be present with the same organic radical. Thus, amixture of methyl chloride and methyl bromide may be used instead ofmethyl chloride alone or a mixture of methyl chloride and methyl iodidemay be used instead of methyl chloride alone in any of the foregoingprocedures 1, 2, 3 or 4. Similarly, a mixture of tertiary butyl chlorideand tertiary butyl bromide or iodide may be used instead of tertiarybutyl chloride alone in any of the foregoing procedures 1, 2, 3 or 4.

The preferred method of practicing the invention is to use a singleGrignard reagent of a type which is easily prepared, such as, forexample, methyl magnesium chloride or ethyl magnesium chloride or otherGrignard reagents derived from primary alkyl halides and magnesium. Thedesired product is then obtained by adding two more organic halides tothe electrolyte as extraneous organic halides. This method ofcontrolling the reaction is especially important where it is desired tomake organic lead compounds in which the organic radical is a secondaryor tertiary radical because the Grignard reagent containing secondaryand tertiary organic radicals are rather difficult to prepare. As aspecific example where it is desired to prepare organic lead compoundscontaining one or more tertiary butyl radicals the preferred procedureis to electrolyze the lead anode in a solvent solution of a Grignardreagent derived from a primary alkyl halide and magnesium and to add atertiary butyl halide such as tertiary butyl chloride, tertiary butylbromide, tertiary butyl iodide, or mixtures thereof, as the extraneousorganic halide. In this way, for instance, by employing methyl magnesiumchloride as the Grignard reagent and adding tertiary butyl chloride asthe extraneous halide lead compounds are produced containing methylradicals and tertiary butyl radicals linked directly to metallic lead.Specific examples of such compound are dimethyl-ditertiary butyl leadand trimethyl tertiary butyl lead. Similarly, ethyl tertiary butyl leadcompounds are obtained by employing ethyl magnesium chloride or thecorresponding bromide or iodide as the Grignard reagent and addingtertiary butyl chloride, bromide or iodide as the extraneous halide.

The cathode may be composed of a suitable conducting but non-reactivematerial, such as platinum, stainless steel, ordinary steel, graphite,or other conducting material, which does not dissolve in theelectrolyte. In some cases the cathode may be composed of the samematerial as the anode. Thus, both the cathode and the anode can becomposed of lead. It is preferable, however, that the anode be composedof lead and the cathode of steel.

The solvent for the Grignard reagent must be relatively inert under theconditions of the process. For this purpose it should not contain anylabile hydrogen which is readily reactive. It may have some dielectricproperties but it should have sufiicient conductivity to permit thepas-sage of a current between the anode and the cathode. Solventscontaining aliphatic hydrocarbon groups connected to oxygen atoms ornitrogen atoms are especially useful. Low boiling solvents, such as,diethylether, can be employed but are difiicult to handle and requirespecial methods for the separation of the organic metallo compounds.Solvents, such as, tetrahydrofuran, can be employed. Examples of organicether solvents are dimethylether,-.diethylether, and high molecularweight dialkylethers, including the ethers of polyoxyethylene glycols,polyoxypropylene glycols and polyoxyethylene-polyoxypropylene glycolswhich are liquid under the conditions of reaction. Special mention maybe made of the dimethylether of diethylene glycol, the dipropylether ofdipropylene glycol, the dibutylether of diethylene glycol and thedimethylether of dipropylene glycol. Examples of solvents containingnitrogen are trihexylamine, triamylamine, pyridine and quinoline.

The temperatures used are normally above the freezing point of thesolution and below the boiling points of the solvent and the desiredorganic lead compound. In general, it is preferable to use temperatureswithin the range of 20 C. to 50 C.

The pressures used are normally sufficient to maintain the liquid phasewith the particular solvent and temperature conditions employed. It isusually preferable to operate the process under a superatrnosphericpressure which does not exceed five atmospheres.

One way of carrying out the process is to electrolyze the electrolyteuntil the Grignard reagent therein is substantially exhausted. Anotherway is to separate a part of the electrolyte and recover at least a partof the desired product, thereafter returning separated solvent and alsoGrignard reagent to the cell. The present invention is not particularlyconcerned with the manner in which the product is recovered.

The invention Will be further illustrated but is not limited by thefollowing examples in which the quantities are stated in parts by weightunless otherwise indicated.

Example I The process can be carried out in various types of cells butone cell which has been found to be particularly suitable is a pipe cellmade from a 2 inch diameter steel pipe about 30 inches long with /2 inchflange openings welded on opposite sides of the pipe 24 inches apart toform inlet openings for introducing and withdrawing the electro lyte.The center of the bottom inlet opening is about 2 inches from the bottomof the cell and the center of the top outlet opening is about 4 inchesfrom the top of the cell. A layer of fine mesh woven polypropylenefilaments is used as a liner on the inside of the pipe to separate thecathode from lead pellets which form the anode material. A lead rod isinserted into the center of the cell longitudinally and connected to apositive source of electricity. A negative source of electricity isconnected to the outside of the pipe so that the pipe itself forms thecathode. The area of the cathode is approximately 92 square inches. Thearea of the screen is approximately 84.25 square inches. The availablevolume within the cell is approximately 18.65 cubic inches. The cell ischarged with lead pellets.

A methyl Grignard solution is prepared by reacting 4 methyl chloride andmetallic magnesium in the dibutylether of diethylene glycol inproportions of approximately one mole of methyl chloride per mole ofmetallic magnesium per mole of said ether. The solution is recirculatedexternally of the cell through a heat exchanger at an average flow rateof '4 gallons per minute until a temperature of 38C. is obtained.Extraneous tertiary butyl chloride is added to the cell in an amountsufficient to give an initial concentration of 3% by weight of the totalsolution. The current is turned on using a voltage of 30 volts and anaverage amperage of 10 amperes and the electrolysis is continued untilof the Grignard reagent has been converted. During the electrolysisadditional tertiary butyl chloride is added at intervals to maintain aconcentration of 3% by Weight of the solution. The lead productcontaining both methyl and tertiary butyl radicals linked directly tometallic lead is recovered by removal of the solvent.

Example II The procedure is the same as in Example I except that onemole of tetrahydrofuran per mole of Grignard reagent is added to theelectrolyte initially.

Example 111 The procedure is the same as in Example I except that 4.5moles of benzene per mole of Grignard reagent is added to theelectrolyte initially.

Example IV The procedure is the same as in Example I except that onemole of tetrahydrofuran per mole of Grignard reagent and 4.5 moles ofbenzene per mole of Grignard reagent are added to the electrolyteinitially.

Example V The procedure is the same as in Example I except that 0.3 moleof methyl chloride per mole of Grignard reagent and 0.6 mole of tertiarybutyl chloride per mole of Grignard are maintained in the electrolyte.

Example VI The procedure is the same as in Example 11 except that 0.3mole of methyl chloride per mole of Grignard reagent and 0.6 mole oftertiary butyl chloride per mole of Grignard reagent are maintained inthe electrolyte.

Example VII The procedure is the same as in Example III except that 0.3mole of methyl chloride per mole of Grignard reagent and 0.6 mole oftertiary butyl chloride per mole of Grignard reagent are maintained inthe electrolyte.

Example VIII The procedure is the same as in Example 1V except that 0.3mole of methyl chloride per mole of Grignard reagent and 0.6 mole oftertiary butyl chloride per mole of Grignard reagent are maintained inthe electrolyte.

Example IX The procedure is the same as in Examples 1 to IV,respectively, except that 0.45 mole of methyl chloride per mole ofGrignard reagent and 0.9 mole of ethyl chloride per mole of Grignardreagent are maintained in the electrolyte. In this example no tertiarybutyl chloride is used. The concentration of methyl magnesium chloridein the solution is 1.4 millimoles per gram of solution. The averagecurrent is 10 amperes and the voltage averages 28 volts. The product isa mixture of organic lead compounds, including tetraethyl lead,tetramethyl lead, triethylmethyl lead, diethyldimethyl lead andtrimethylethyl lead. The run is carried out for 20 hours.

Example X The procedure is the same as in Example I except that phenylchloride is used in place of tertiary butyl chloride and the run iscarried out for 20 hours.

.a period of 20 hours.

- The-procedure is the "Example-XI ,Tbe 'proeeduil is the same as inExample 'lp'except that cyfclohexyl chloride is used in placeo'ftertiary butyl chloride and the ru'n'is' carried out for hours."

.. Example XII "The*proced'ure'-is the same as in Example -'-I-'-'exceptthat'theGrignardreagent consists of a mixtureof methyl magnesiumchloride" and ethyl magnesium chloride dissolved in the dibutylether ofdiethylene glycol'in proportions of about 1 mole of said diether permole'of the inixedGrignard reagents. The temperature of the-solutio'n ismaintained at C.,' extraneous tertiary butyl chlorid'e'is' added to-the"solution in an amount initiall'y' corresponding to 0.5 mole per'mole ofmixed Grignard and this concentration ism'aintained by-adding additional'am'ount's-of-tertiary butyl chloride as needed during the =process-.The run'is carried' out for-10 hours at a voltage of 28 volts and anaverage amperage of 6 amperes. The product is a mixture of organic leadcompounds containing' methyli ethyl and tertiary 'butyl radicals linkedtomet-alli'c lead. e f "-Examp1eX-III j Theprocedure is the same'asinExample XII except that 1 mole of tetrahydrofuran per mole of totalGrignard .reagent is added to the electrolyte initially and the r'uniscarn'edout with an average current of 10 amperes for Example Theprocedure is the same as in Example'XII except that one mole oftetrahydrofuran per mole of total Grignard reagent and 4.5 moles ofbenzene per mole of total Grignardzreagent areaddedto the electrolyteinitial- 1y. .The run is carried out at a temperature of C.

for 11.5-hours at an'a'ver-age current of 20 amperes and an averagevoltage of 29volts.

Example same as in Examples XII,

and XIV, respectively, except that 0.45 mole of methyl chloride "per'mole'; of totalflmixed Grignard reagents i maintained inthe'solution;during the'proc'ess, I

I The'procedure-is the same as that described in .ples XII, XIII .andXIV, respectively, except that 0.7

mole of, extraneous ethyl chloride per mole of totalmixed Grignardreagents is maintained in the solution-during the process; Y

. It will be understood that in the foregoing examples secondary butylchloride can-besubstituted for tertiary butyl chloride. Likewise,isobutyl chloride can be sub- -stituted: for tertiary 'butyl chlorideinthe examples.

Similarly,z-other organic halidescan be used either by 'employing two ormore organic halides with a single Grignard-reagent orhy employing twoor more organic halides with a mixed'Gri'gnard reagent or by employ-:ing'a singleporganic halide with a mixed Grignard reagent. .In anycase, products areobtained containing at, least two different organicradicals linked to metallic lead.

-As .previously indicated the invention is especially extraneous organichalides which do not readily iorm Grignard reagents, includingparticularly tertiary .butyl :chloride,. tertiarybutyl bromide andtertiary butyl iodide and other =organic halides containing-4 to 18carbon "atoms. W 1 I f --The optimum conditions will vary :dependingupon {the particular-organichalides used but it is,;preferable jtooperate with a total concentration of extraneous organic halides withinthe'range of 0.1 to 1.1 moles per mole of total GrignardreagentpThereaction can.be'con-.-;

trolled by .varying the respective concentrations, of the ,two or moreorganic halides used in carrying out the process..

Itwillbe recognized that various methods, includingfractionaldistillation, vacuum distillation and steam distillation, maybe employed in recovering the products.

The present-invention is not concerned with the particular manner inwhich the products are recovered nor is it concerned with the particularsolvents used for the Grignard reagent. Furthermore, the critical pointof the invention does not lie in the particular voltages or amperagesused. These may varywithin relatively wide limits. Thus, the voltagesare usually within the ranges of 2 to 35' volts and the currentrequirements are normally :within the-range of 2 ,amperes to 30 amperes.The current .density will usually vary within the range of about 2amperes per square foot to 30 amperes per square .foot. The optimumcurrent density will vary somewhat depending upon the temperature. In-genera1, the higher the temperature used, the higher the currentdensity. The temperatures of 30 C., 35 C., 40 C., 45 C.,

.and- 50 C. can be used with satisfactory results. 'In some .of theexamples, tetrahydrof-uran has been added because it has been found thatthis addition increases the conductivity initially and shortens the run.This results in less gas formation due to the shorter run. However, theprocess may be carried out without tetrahydrofuran. Wheretetrahydrofuran is employed it is preferable to use about 0.5 to 1.5moles per mole of total -Gri'gnard reagent. Higher concentrations appearto produce side reactions or side physical effects which areundesirable.

In carrying out the process the initial Grignard concentration issubject to wide variation but is preferably within the range of 0.5 to2.5 millimoles per gram of l'hydrocarbon, such as benzene, are employed,it is preferable to use an amount within a weight ratio oftetrahydrofuran to aromatic hydrocarbon of 1:4 to 1:7.

The initial Grignard solution preferably contains at least one mole permole of total Grignard reagent of a dialkylether of a polyoxyalkyleneglycol containing 2 to '4 oxygen atoms in the glycol,'2 to -4 carbonatoms in the alkylene groups of the glycol, and 2 to 8 carbon atoms inthe alkyl groups of the ether radicals.

It will be seen from the foregoing description that the 'presentinvention makes it-possible to prepare organic compounds of lead inwhich at least two different organic radicals are'linked to the leadatom. Specific examples of such compounds 'arethose in which methyl andethyl radicals are linked to lead, or those in which methyl and propylradicals are linked to lead, or those in which ethyl and propyl radicalsare linked to lead, or those in which methyl and isopropyl radicals arelinked to lead, or those in which ethyl and isopropyl radicals arelinked to lead, or those in which methyl andn-butyl radicals are linkedto lead, or those in which methyl and isobutyl radicals are linked tolead, or those in which methyl and secondary butyl radicals are linkedto lead, or those in which methyl and tertiary butyl radicals are linkedto lead, or those in whichethyl and n-butyl radicals are .linked tolead, or those in which ethyl and isobutyl radicals are linked to-lead,or those in which ethyl and secondary butyl radicals are linked to lead,or those in 'whichethyl and tertiary butyl radicals are linked to lead,or those in which methyl and amyl radicals are and tertiary amylradicals are linked to lead, or those in which ethyl and amyl radicalsare linked to lead, or those in which ethyl and isoamyl radicals arelinked to lead, or those in which ethyl and tertiary amyl radicals arelinked to lead, or those in which propyl and n-butyl radicals are linkedto lead, or those in which propyl and secondary butyl radicals arelinked to lead, or those in which propyl and tertiary butyl radicals arelinked to lead, or those in which isopropyl and n-butyl radicals arelinked to lead, or those in which isopropyl and secondary butyl radicalsare linked to lead, or those in which isopropyl and isobutyl radicalsare linked to lead, or those in which isopropyl and tertiary butylradicals are linked to lead, or those in which methyl and phenylradicals are linked to lead, or those in which ethyl and phenyl radicalsare linked to lead, or those in which propyl and phenyl radicals arelinked to lead, or those in which isopropyl and phenyl radicals arelinked to lead, or those in which butyl and phenyl radicals are linkedto lead, or those in which isobutyl and phenyl radicals are linked tolead, or those in which secondary butyl and phenyl radicals are linkedto lead, or those in which tertiary butyl and phenyl radicals are linkedto lead, or those in which methyl and cyclohexyl radicals are linked tolead, or those in which ethyl and cyclohexyl radicals are linked tolead, or those in which propyl and cyclohexyl radicals are linked tolead, or those in which isopropyl and cyclohexyl radicals are linked tolead, or those in which n-butyl and cyclohexyl radicals are linked tolead, or those in which secondary butyl and cyclohexyl radicals arelinked to lead, or those in which isobutyl and cyclohexyl radicals arelinked to lead, or those in which tertiary butyl and cyclohexyl radicalsare linked to lead, or those in which ethyl and benzyl radicals arelinked to lead, or those in which propyl and benzyl radicals are linkedto lead, or those in which isopropyl and benzyl radicals are linked tolead, or those in which n-butyl and benzyl radicals are linked to lead,or those in which secondary butyl and benzyl radicals are linked tolead, or those in which isobutyl and benzyl radicals are linked to lead,or those in which tertiary butyl and benzyl radicals are linked to lead,and the like.

An important feature of the invention resides in the fact that the typeof organic radical linked to lead can be controlled by controlling thekind and quantity of the extraneous organic halides, especially wheretwo extraneous organic halides are used wherein one of the organicradicals of the organic halide is different from the organic radical ofthe other organic halide. In such a case, where the reaction is startedwith a single Grignard reagent, mixtures of Grignard reagents mayultimately be formed and the nature of such mixtures will depend uponthe kind and amount of the organic halides added. While the invention isespecially useful where the organic radicals of the hali'de are alkylradicals, such as methyl, ethyl, propyl, isopropyl, n-butyl, secondarybutyl, isobutyl, tertiary butyl, amyl, isoamyl, tertiary amyl, hexyl,and higher homologues, it is also useful where the organic radicals arecyclo aliphatic, such as cyclohexyl or cyclopentyl, or where they arearomatic, such as, phenyl, or where they are aralkyl, such as benzyl.

The invention is hereby claimed as follows:

1. A process for preparing organic lead compounds containing differentorganic radicals linked to the same metallic lead atom which compriseselectrolyzing, using a lead anode, a substantially anhydrous solution ofat least one Grignard reagent in a substantially inert solvent for saidGrignard reagent, and adding at least one extraneous organic halide tosaid solution, the organic radical of at least one said organic halidebeing dilferent from the or ganic radical of at least said Grignardreagent.

2. A process as claimed in claim 1 in which at least one said Grignardreagent is formed from a primary alkyl halide and magnesium and at leastone said extraneous organic halide is a tertiary alkyl halide.

3. A process for preparing organic lead compounds containing differentorganic radicals linked to the same metallic lead atom which compriseselectrolyzing, using a lead anode, a substantially anhydrous solutionwhich initially contains only one Grignard reagent in a substantiallyinert solvent for said Grignard reagent, and adding a plurality ofextraneous organic halides to said solution, the organic radical of atleast one of said organic halides being different from the organicradical of said initial Grignard reagent.

4. A process as claimed in claim 3 in which said Grignard reagent is analkyl Grignard reagent formed from a primary alkyl halide and magnesiumand at least one of said extraneous organic halides is an alkyl halide.

5. A process for preparing organic lead compounds containing differentorganic radicals linked to the same metallic lead atom which compriseselectrolyzing, using a lead anode, a substantially anhydrous solution ofmethyl magnesium chloride in a substantially inert solvent for saidmethyl magnesium chloride, and adding a plurality of differentextraneous alkyl chlorides to said solution.

6. A process as claimed in claim 5 in which at least one of saidextraneous alkyl chlorides is ethyl chloride.

7. A process as claimed in claim 5 in which at least one of saidextraneous alkyl chlorides is tertiary butyl chloride.

8. A process for preparing organic lead compounds containing differentorganic radicals linked to the same metallic lead atom which compriseselectrolyzing, using a lead anode, a substantially anhydrous solution ofethyl magnesium chloride in a substantially inert solvent for said ethylmagnesium chloride, and adding a plurality of different extraneous alkylchlorides to said solution.

9. A process for preparing organic lead compounds containing dilferentorganic radicals linked to the same metallic lead atom which compriseselectrolyzing, using a lead anode, a substantially anhydrous solution ofmethyl magnesium chloride in a substantially inert solvent for saidmethyl magnesium chloride, and adding both methyl chloride and ethylchloride to said solution during the electrolysis.

10. A process for preparing organic lead compounds containing differentorganic radicals linked to the same metallic lead atom which compriseselectrolyzing, using a lead anode, a substantially anhydrous solution ofmethyl magnesium chloride in a substantially inert solvent for saidmethyl magnesium chloride, and adding both methyl chloride and tertiarybutyl chloride to said solution during the electrolysis.

11. An electrolyte for making organic lead compounds comprising asubstantially anhydrous solution of at least one Grignard reagent in asubstantially inert solvent for said Grignard reagent and at least oneextraneous organic halide, and the organic radical of at least one saidGrignard reagent being different from the organic radical of at leastone said organic halide, the total concentration of extraneous organichalides being within the range of 0.1 to 1.1 moles per mole of totalGrignard reagent.

12. An electrolyte for making alkyl lead compounds comprising ananhydrous solution of at least one Grignard reagent in which the organicradical is an alkyl radical and a plurality of extraneous alkyl halideshaving different alkyl groups from one another, all dissolved in asubstantially inert solvent for the Grignard reagent and the alkylhalides, the total concentration of said extraneous alkyl halides beingwithin the range of 0.1 to 1.1 moles per mole of said Grignard reagent.

13. An electrolyte for making organic lead compounds comprising asubstantially anhydrous solution of at least one Grignard reagent in asubstantially inert solvent for said Grignard reagent and at least oneextraneous organic halide, and the organic radical of at least one saidGrignard reagent being different from the organic radical of at leastone said organic halide, the total concentration of extraneous organichalides being within the range of 0.1

to 1.1 moles per mole of total Grignard reagent, and the Grignardconcentration being within the range of 0.5 to 2.5 millimoles per gramof solution.

14. An electrolyte for making alkyl lead compounds comprising ananhydrous solution of at least one Grignard reagent in which the organicradical is an alkyl radical and a plurality of extraneous alkyl halideshaving different alkyl groups from one another, all dissolved in asubstantially inert solvent for the Grignard reagent and the alkylhalides, the total concentration of said extraneous alkyl halides beingwithin the range of 0.1 to 1.1 moles per mole of said Grignard reagent,and the Grignard concentration being within the range of 0.5 to 2.5millimoles per gram of solution.

15. An electrolyte for making alkyl lead compounds comprising ananhydrous solution of at least one Grignard reagent in which the organicradical is an alkyl radical and a plurality of extraneous alkyl halideshaving difierent alkyl groups from one another, all dissolved in asubstantially inert solvent for the Grignard reagent and the alkylhalides, the total concentration of said extraneous alkyl halides beingwithin the range of 0.1 to 1.1 moles per mole of said Grignard reagent,said Grignard reagent being formed from a primary alkyl halide andmagnesium and at least one of said extraneous alkyl halides being fromthe group consisting of secondary and tertiary alkyl halides.

16. An electrolyte for making alkyl lead compounds comprising ananhydrous solution of at least one Grignard reagent in which the organicradical is an alkyl radical and a plurality of extraneous alkyl halideshaving different alkyl groups from one another, all dissolved in asubstantially inert solvent for the Grignard reagent and the alkylhalides, said solvent containing at least one mole per mole of totalGrignard reagent of a dialkylether of a polyoxyalkylene glycolcontaining 2 to 4 oxygen atoms in the glycol, 2 to 4 carbon atoms in thealkylene groups of the glycol, and 2 to 8 carbon atoms in the alkylgroups of the ether radicals, up to 1.5 moles of tetrahydrofuran permole of total Grignard reagent, up to 7.5 moles of henzene per mole ofGrignard reagent, 0.1 to 1.1 moles of said extraneous alkyl halides permole of Grignard reagent, and a Grignard concentration of 0.5 to 2.5millimoles per gram of solution.

17. An electrolyte as claimed in claim 16 in which the Grignard reagentsare from the group consisting of methyl magnesium chloride, ethylmagnesium chloride, and mixtures thereof and the alkyl halides aremethyl chloride and ethyl chloride.

References Cited UNITED STATES PATENTS 3,088,885 5/1963 McKay 204-593,007,857 11/1961 Braithwaite 204-59 3,007,858 11/1961 Braithwaite204-59 2,535,193 12/1950 Calingaert et al 260-437 FOREIGN PATENTS839,172 6/1960 Great Britain.

OTHER REFERENCES Pearson et al., Transactions of the ElectrochemicalSociety, vol. 82 (1942), pp. 297304.

HOWARD S. WILLIAMS, Primary Examiner.

JOHN R. SPECK, JOHN H. MACK, WINSTON A.

DOUGLAS, Examiners.

B. JOHNSON, Assistant Examiner.

